water based is eyesafe, alcohol is not. if i remember correctly, they retail for about $12 USD, give or take. there's an eyeliner one, and a mascara one as well. mixing mediums are available only at pro stores, or by calling the pro 1800 number.
i used the water based one by dropping a couple drops into a plastic artist palette, tapping a small amount of pigment into it, and mixing it, then applying it wherever i wanted the color. there was less fallout, obviously, since you're working with a liquid, instead of loose powder, and also, the color payoff was more intense, and the pigment seemed to last longer on the skin. when i go back to the pro store, i want to pick up the eyeliner one..